The Promise
by alecsangryface
Summary: Alec just wants Jace to be happy. Jace just wants Alec to be happy. They both make a promise.


**A/N: This was originally written for 200 followers on my tumblr: alecsangryface (I live for self-promo) but that was a while ago and this just kept feeding itself so editing was a bitch. Anyway, have some jalec and enjoy.** **(and maybe review but don't feel like you have to)**

 **The Promise**

 _Alec first made the promise exactly one week after Jace had started living at the Institute._

He was harshly woken from his pitiful state of sleep by the ear-splitting scream forcing its way into his room through paper thin walls, it would be surprising if Alec was the only one who heard it. He didn't even think as he rushed out of the room, barely managing to grab his witchlight as he went, and into Jace's room next door.

His heart broke at the sight of the boy tossing furiously around the bed, harsh whimpers mixing with the ruffling of unworn sheets. Alec didn't know how to proceed, Izzy had always woken up from her nightmares by herself before she went to get in bed with Alec. Jace's was different, he was trapped.

So he waited. He didn't want to wake Jace in case it would do him more harm than good. He didn't know how long he waited, but when Jace finally stopped tossing and slowly began to start waking up properly, Alec silently made his way over to the side of the bed, the glow of the witchlight letting Jace know he was there.

"Are you feeling okay?" He whispered. It was a pretty lame conversation starter in his opinion, but he didn't want to pressure Jace into talking about what he wasn't comfortable with. Jace didn't reply for a long while, just stared up at the ceiling; eyes unfocused and empty, while Alec perched himself on the edge of the mattress being careful not to get too close to Jace.

"I saw it happen again. My father-" Jace whispered eventually, choking on a sob. Alec didn't know how to reply, what does one say when someone they barely know confesses to reliving seeing their father murdered over and over again.

"It's alright you know" Alec began quietly. He continued on despite Jace's angry glare pointed towards him, "Everyone has nightmares. Don't be mad at yourself"

"It's weak. I'm weak" Jace whispered angrily, his eyes alighting with a fire that Alec hadn't noticed in him before. He hesitantly placed a hand on Jace's arm, attempting to comfort him in the only way he knew. He wasn't good with words, and touching made him uncomfortable but it always made Isabelle feel better so he hoped it worked for Jace too.

"You're not weak, Jace" Alec replied just as intensely, "Izzy has nightmares sometimes. I do too. Do you think we're weak?"

Jace looked away ashamedly but he still made no attempt to get Alec to leave, so he shuffled further onto the bed and laid down on his back next to the other boy.

"What are you doing?" Jace asked him.

"Two warriors are stronger than one right? You can't possibly be weak if there's two of us" He whispered back, hoping that Jace wouldn't force him to leave. With the sudden revelation that Jace wasn't doing as well as he wanted everyone to believe, Alec began to feel how he would with his brother and sister. Fiercely protective.

When Jace rolled over, shuffled a little bit closer to Alec and shyly twisted their hands together, drawing comfort from the closeness he had been denied in his life thus far, Alec allowed himself to smile slightly. He let the witchlight slip from his fingers and plunge the room into total darkness. Then before he fell completely asleep, he promised that he would do everything in his power to make Jace happy.

 _Jace made the same promise later. A year later to be exact._

He had adjusted to life at the Institute. He was grateful for both Alec and Isabelle, who had welcomed him into their lives as easily as they had with Max when he was first born, and he was grateful that Robert and Maryse didn't hit him or shout at him like his father had. Alec and Izzy were very lucky to have them as their parents, or at least he had thought.

He was hiding in the library, intent on being alone on the anniversary of his father's death. He may have been moving on slowly, but he definitely wasn't over it yet. The library was large, not a large as the one in his old home, but large enough that he could sneak away into the classical literature section to hide away amongst the Dickens' novels.

He was fingering the spine of _Great Expectations_ when he heard Robert. He crept as quietly as he could through the rows of books, curious enough to want to know what was happening but not enough to reveal himself. He hadn't ever heard Robert as angry as he sounded right then.

Alec was stood in front of his father, hands folded behind his back and staring impassively. It was not an expression a twelve year old should have been at ease wearing. Jace's eyes narrowed in confusion and anger, whatever it was Alec had done (and it was probably nothing, he never did anything bad unless Jace convinced him to) he definitely didn't deserve what Robert was saying to him.

"I will not have my son disappoint me in this way" Robert spat in his sons face. Alec didn't even flinch, didn't even react in anyway. "I don't want to see this again"

Robert slammed the book he had been holding into Alec's chest. Alec scrambled to grab onto it before it could hit the floor, the only sign that he cared, as Robert stormed away. Jace shrunk back into the shadows as he passed him. Once he was certain he was gone, Jace eased his way into the light so he could see Alec again.

He was just in time to see Alec wipe furiously at his cheek where a stray tear had fallen. His knuckles were white on the book, as if the harder he held it the easier it would be to keep himself from falling apart. He fell to his knees, his eyes screwing shut and his body rocking as he repeated words that Jace couldn't hear like a mantra.

Alec suddenly looked up. His eyes narrowed and his gaze hardened. Jace stifled his gasp at the look, a look that should never have been on Alec's face. As Alec stalked off, _Henry IV_ still clutched desperately in his hands, Jace promised himself that he would do his upmost to make Alec happy again.

They both felt a rush of happiness when their parabatai ritual was finished and their bond was sealed. But the feeling was so overwhelmingly AlecandJace that it was difficult to pinpoint who felt it first. Was it Alec's happiness causing Jace's? Or was it the other way around? It didn't matter where it started for them as long as the other one was happy. Keeping their promise and seeing their best friend with a smile that lit up their entire being was enough to keep them going through anything.

Yet, they lost sight of their bond and their promise somewhere along the way. Jace became more confrontational, angry that the world was an unfair as it had ever been and there was nothing he could do about it. Alec became more closed off, shutting himself away so he would never be in the way of his own duty to his family. It got worse during the wars before it ever got better, both caught up in their own selfish desires to even consider the other for even the briefest of seconds. The severance of their bond during the Dark War was the wake-up call both needed to recognise how far they had moved away from their promise.

 _They both realised that they didn't need their promise later on. There were others that would keep it for them._

Alec took a deep breath to steady himself before he pushed his way through the door in front of him and into the room where Jace was hyperventilating. He took a moment to admire how good Jace looked in gold, the shine setting off his own skin tone, having never looked as angelic as he did before. But Alec didn't let that last long before he was rushing across the room and leading Jace over to a chair.

"What's wrong? What can I do?" Alec asked, it had been some time since Jace had ever gotten as worked up about anything so Alec was out of touch with the 'What to do when Jace is freaking out' rule book.

"I'm getting married" Jace whispered, his eyes wide and desperate as they finally locked onto Alec's, "I'm getting married" he repeated. Alec was shocked when he started crying, they had never been ones for sharing in their feelings – and it had gotten them into trouble on more than one occasion – so he was a bit taken aback.

"Yes" He began slowly, his eyebrows furrowing in concern for his brother, "You have been planning this for six months?"

"I know that, idiot" Jace suddenly jumped up from his seat and threw his arms around Alec's neck. Alec staggered at the force of it, but he held on as tightly as Jace was. He was glad that Jace was a little bit more forthcoming when it came to expressing himself, "I'm just sort of" he made a noise "because it's actually happening"

"And you're happy?" Alec asked snuffling as Jace's hair tickled his nose.

"Of course I am" Jace pulled back but he didn't completely let go of Alec, "I'm marrying the most incredible girl, surrounded by everyone we love. I couldn't not be happy" Alec smiled but didn't reply. He didn't have to, Jace knew exactly how happy for him he was.

The top table during the reception was small. Just six of them, the six that had saved the world on a number of occasions, which seemed fitting. Alec was sat next to Jace in the place of Best Man and Magnus was seated next to him. Isabelle was next to Clary in the place of Maid of Honour and Simon was sat next to her.

"Do I have to make a speech?" Alec grumbled to Jace, who immediately started laughing.

"As my parabatai, it is your duty to do so" Jace clapped him on the back and shared a shrug with Magnus, "I don't expect it to be very funny or very good for that matter. The fact that you'd do it means enough to me"

Alec rolled his eyes but stood anyway, appreciating the blue sparks Magnus sent in the air to get the receptions attention.

"So Jace tells me that it is my duty as his Parabatai to make a speech. If I had known that when we were twelve I would have told him where he could stick the ritual" Jace socked him on the arm but Alec continued on with barely a glance in his direction, "I guess I'm supposed to tell you all the stories of Jace's stupidity over the years, and while I could regal you with the tale of his first experience with alcohol or his first time officially hunting. But they have nothing on the stupidest moment of his life. Meeting Clary Fray"

There was a rumble of noise that maybe sounded like dissatisfaction and awkwardness. Alec glanced down the table at Clary and she was smiling knowingly at him so he continued.

"Here she was completely oblivious to our world and Jace was immediately interested. I hated her. I spent more time worrying about my parabatai's whereabouts and well-being than was healthy, and she fulfilled I promise that I made a week after I met Jace that I wasn't doing so well at keeping" He twirled the champagne glass between his fingers and gripped Jace's shoulder with his other hand, "I had promised to myself to do whatever possible to make sure Jace was happy and I wasn't doing very well. Clary did that almost immediately and I'm so grateful for her coming into our lives because of that, even if she did end up causing me more stress than I would have liked"

Clary chuckled. She leant her head on Jace's shoulder and rubbed his arm with a smile as he sniffled. He wasn't crying, or at least he was trying not to.

"I guess I have Clary to thank for my own happiness as well. If it weren't for her almost sabotaging our mission I would have never met Magnus, and I wouldn't have a son" Alec looked down to Jace, both with happy tears in their eyes, "And I would have still been pining after my best friend and would have lost him in the process. I thank the angel every day for you two, Jace and Clary, because although I have spent many a sleepless night worrying because of you, you both have made me so happy. And I can only hope that I can return the favour one day. I love you both."

Alec shook his head and coughed in an attempt to dislodge the lump in the back of his throat. He raised his glass again as he returned his attention to the rest of the reception, "To Clary and Jace, may your happiness be eternal"

There was a low hum of people repeating the words, mixed with laughter and sniffles. Alec smiled when he saw Isabelle handing Clary a tissue from her purse, her own clutched tightly in her hand. Jace stood up to hug him tightly.

"I love you too, Alec" Jace whispered. Alec squeezed him back just as tightly as he was being held. Then they had to let go because Clary was tapping on Jace's shoulder so she could take his place in the hug. She didn't speak. She didn't have to. Alec knew exactly what she was saying with her hug alone.

He smiled as Magnus placed a hand on his forearm when he sat back down. Magnus leant around him to address Jace, "I told you it wasn't going to be terrible. You should have had more faith"

"Yes. Yes" Jace waved a hand dismissively but he did smile almost sheepishly, "I'm sorry I doubted your speech making skills Alec"

"Don't worry about it. I do feel sorry for you though" Alec said smiling like he knew something Jace didn't.

"Why?"

"Well you're going to have a hard time topping that at my wedding" He smirked into his champagne as Jace blanched. He recovered long enough to accept the challenge before he had to make his own speech.

A few years later when Shadowhunters and Downworlders could marry in Shadowhunter ceremonies, Alec and Magnus sat on the top table of their reception eagerly awaiting Jace's speech. He had promised great things.

"Alec told me a few years ago that I would never be able to top the speech he made at my wedding. I'm not even going to attempt to. Instead, we're gonna listen to a couple of stories about Alec and Magnus." He smiled cheekily and tipped his glass towards the two, "How about the night they met? Alec was so mad that we had to go to Brooklyn, he hated it apparently. He spent the entire subway ride complaining that it was against Clave rules, and we should have told someone what we were doing, and he was especially furious that we would be at a party where he may have actually learned to enjoy himself." He ignored the rude gesture from Alec with a smirk.

"Anyway, my point is, Alec turned up to that party as the number one grouch in all of New York. I didn't hate you for it, and I still don't. But seeing how easily Magnus got him to be more open with himself hurt me. What a terrible parabatai I must have been to not see how you were shutting down" Jace turned to look at Alec then, "I made a promise that I would do anything to make you happy and I failed and I'm sorry. I am truly grateful to you, Magnus, that you've made my best friend smile all these years, especially when I was not able to. And Alec. I'm so happy for you. Seeing you like this was all I've wanted since I met you and I'm sorry that I couldn't make it happen for you sooner, but I'm glad that you do get it. I love you buddy"

Alec smiled as Jace made his toasted, "To your continued happiness, Alec and Magnus. And to your health Alec, angel knows you need it" Magnus' smile faltered slightly when Jace mentioned that last part but he recovered long enough to push his husband out of the way so he could hug his brother-in-law.

"I know we have our differences Jace, but I'm glad you're part of Alec's life. Don't sell yourself short, you still make him happy." Magnus mumbled. Jace smiled at the revelation but didn't reply. Magnus didn't need him to and he was sure that if he tried to say anything every emotion he was having would spill over all at once.

"Magnus can I hug my own best man yet?" Alec pulled the two apart with a laugh, pausing to wipe Magnus' tears away and press a tender kiss to his brow. Magnus let Jace go and returned to his seat to talk to Catarina. The parabatai needed as much privacy as they were going to get at a wedding reception.

"Thank you Jace. For everything" Alec said when they finally embraced. They didn't hold each other for too long, just long enough to convey their happiness, and their gratefulness.

"Anything for you, brother" Jace replied as they sat back down. And it was true. For both of them. Despite the hardships and falling apart for a time, they were better now. They were no longer the most important person in the others life, and no longer the main source of happiness for the other. But it didn't matter because they were both happy and that was all they had promised to do.


End file.
